What is a sulcus (groove) or chink (gap) in the vocal cords?

Sulcus Vocalis and Glottic Chink: Anatomical Definitions

A sulcus vocalis is a longitudinal groove or furrow along the free edge of the vocal fold, while a "chink" refers to an incomplete glottic closure gap that occurs during phonation, often resulting from the structural defect created by the sulcus.

Sulcus Vocalis: Structural Pathology

Anatomical Description:

• Sulcus vocalis is defined as a longitudinal depression on the vocal cord, running parallel to its free border 1, 2
• The groove is located at the free edge of the vocal fold and can be unilateral or bilateral 3
• The condition involves deeper layers beyond just the epithelium, affecting the lamina propria and creating fibrotic tension lines 4, 5

Classification System:

• Type I (Physiologic): Superficial groove that may be considered relatively normal and is found in 78% of asymptomatic individuals with sulcus 1, 2
• Type IIa (Vergeture): Deeper groove resembling a "stretch mark" along the vocal fold margin, with variable depth involving deeper lamina propria layers 2
• Type IIb (Pouch): Functions as an open cyst formation 2

The "Chink": Glottic Insufficiency

Mechanism of Gap Formation:

• The sulcus creates a structural defect that prevents complete midline closure of the vocal folds during phonation 4, 2
• This incomplete glottal closure results in a visible gap or "chink" between the vocal folds 2
• The American Academy of Otolaryngology-Head and Neck Surgery defines glottic insufficiency as incomplete closure of the vocal folds, which can result from soft tissue defects like sulcus vocalis 6

Clinical Manifestations

Voice Characteristics:

• Breathiness: The primary symptom caused by incomplete glottal closure and air leakage through the chink 1, 2
• Roughness: Results from decreased mucosal wave amplitude and irregular vibrations of the stiffened vocal fold edge 1, 4, 2
• Hoarseness: Variable severity depending on sulcus depth and bilateral involvement 3
• Vocal fatigue, reduced loudness, and instability during speaking or singing 7

Important Clinical Pitfall:

• Sulcus vocalis is frequently overlooked and misdiagnosed as functional hyperkinetic voice disorder 3
• The condition may be difficult to detect by indirect laryngoscopy alone, particularly in older patients with secondary compensatory changes 3
• Microlaryngoscopy under general anesthesia may be required for definitive diagnosis, but only if the examiner actively searches for the furrow 3

Diagnostic Approach

Laryngoscopic Examination:

• Direct laryngoscopy is essential for visualization, as the furrow can be subtle 3
• Stroboscopy helps assess the vibratory pattern and mucosal wave abnormalities 2
• Vocal fold palpation under general anesthesia remains the gold standard for diagnosis 5
• The American Academy of Otolaryngology-Head and Neck Surgery recommends laryngoscopy with stroboscopy to detect subtle alterations in vocal cord movement 8

Key Diagnostic Features:

• Look for a longitudinal groove parallel to the free edge of the vocal fold 1, 2
• Assess for incomplete glottic closure during phonation (the "chink") 2
• Evaluate mucosal wave amplitude reduction and stiffness of the free edge 4, 2

Etiology Considerations

Controversial Origins:

• Both congenital and acquired theories exist, with recent evidence supporting multiple etiologies including congenital, inflammatory, and acquired mechanisms 5
• The condition is often found in younger patients, suggesting congenital origin in many cases 3
• Recent literature demonstrates the role of epithelium in pathogenesis, not just absence of superficial lamina propria 5

Treatment Implications

Conservative Management:

• Voice therapy should be the initial approach, particularly for Type I sulcus 4, 5
• The American Academy of Otolaryngology-Head and Neck Surgery recommends voice therapy for most voice disorders as it is effective but underutilized 8

Surgical Considerations:

• Phonosurgery options include the "slicing mucosa" technique to detach the sulcus mucosa and interrupt fibrotic tension lines 4
• Surgical results are often disappointing and variable, with no gold standard treatment established 2, 5
• Critical counseling point: Patients must be intensively informed that surgery mainly increases voice loudness rather than achieving complete normalization 2
• The American Academy of Otolaryngology-Head and Neck Surgery states that surgery for benign vocal fold lesions should be reserved for cases where satisfactory voice cannot be achieved with conservative management 6

Realistic Expectations:

• Even asymptomatic individuals with sulcus vocalis may exhibit slight changes in vocal quality and roughness 1
• Treatment aims for anatomical and functional improvements rather than complete restoration to normal 4